Guys, is this ok?

So there is a guy at work that really flirts with me. Now I will be leaving for school in two weeks, but he pretty much invited himself up to my school... when I told him he could he sounded really suprised. Now, he hasn't asked me for my number. I feel like we get to that moment a lot, but he never asks. Like one time he told me he wanted to write me letters, and I said you could just text me them like a normal person, then it seemed as though he wanted to ask. Then he always tells me I'm pretty, and I'm smart, what is happening? Is he interested, an is it ok for me to ask him?